1. Field of the Invention
The present invention relates to a ceramic circuit substrate and a semiconductor device using the same. More specifically, this invention relates to a ceramic circuit substrate having a feature in the constitution of junction portions of the external connection terminals and a semiconductor device using such a substrate.
2. Description of the Related Art
Semiconductor devices of the surface mounting type such as BGA (ball grid array)-type semiconductor devices have a problem in that, when the semiconductor devices are mounted, the external connection terminals are broken due to the thermal stress caused by a difference in the coefficient of thermal expansion between the mounting substrate and the semiconductor package. When a semiconductor device using a ceramic circuit substrate as a main body is mounted on a resin substrate such as printed substrate, in particular, the thermal stress due to a difference in the coefficient of thermal expansion becomes a problem since the coefficient of thermal expansion of the ceramic is from about 4 to 7.times.10.sup.-6 /.degree. C. whereas the thermal expansion of the resin substrate is about 15.times.10.sup.-6 /.degree. C.
In practice, when an alumina ceramic package having a coefficient of thermal expansion of about 7.times.10.sup.-6 /.degree. C. is mounted on a resin substrate such as of BT (bismaleimide triazine) resin, a package size of 25 mm square is a limit that can be mounted from the standpoint of reliability of the external connection terminals against the thermal stress. When a semiconductor device using a ceramic substrate as a main body is mounted on a resin substrate, as described above, limitation is imposed on the size of the package. Accordingly, a limitation is imposed on the number of the external connection terminals.